1. Pregnancy and Birth
Chapter 17.2
Page

2. Objectives Describe the process of fertilization and implantation
Trace the development of a fertilized egg to the birth of a baby
List the events of birth
Explain how a mother’s health can affect the health of her baby

3. Key Terms
Fetus
Zygote
Blastocyst
Embryo
Amniotic fluid
Placenta

4. A process: From fertilization to growing fetus
Fertilization is the union of a mature egg cell with a single sperm
Sperm cell bind to the egg while it is in the fallopian tube
Chemicals in the “head“ of the sperm cell weaken the outer coating of the egg
A single sperm cell breaks through and the egg changes chemically to prevent other sperm from entering
The genetic materials combine and fertilization is done

5. The Zygote (fertilization to 2 days)
The egg and sperm combine to form a new structure called the zygote
All of the trillions, (1,000,000,000, 000), 0f cells are generated by this single cell
If the single cell separates into two or more separate groups at this early stage it may result in multiple births, (twins or triplets)
If more than one egg is fertilized, there are multiple zygotes, (fraternal twins or triplets)

6. The Embryo (2 days to 2 months)
As the zygote divides and moves toward the uterus it becomes a ball of cells called the blastocyst
The blastocyst makes a hormone called HCG that tells the ovary that pregnancy has begun
As it attaches to the uterus it now is called an embryo and has no major structures yet
The amniotic sac and placenta begin developing

7. The Fetus (2 months after fertilization)
The placenta nourishes the fetus
Nutrients and oxygen are provided
Wastes and CO2 are removed
There is no contact between the blood of the fetus and the mother because of this barrier
The umbilical cord is the point of connection
The fetus grows for about 9 months and develops specialized structures

8. Trimesters First trimester Second trimester Third trimester
Major organs have begun to form
Eyes, ears, liver, lungs, heart and brain
Bones, muscles, arms, and legs
Second trimester
Movement, heartbeat, blinking
Third trimester
All organs rapidly complete development
The brain grows rapidly, (and continues after birth)
The fetus gains weight

9. Birth The timing of birth Labor
Babies born before 35 weeks are considered premature or “preemies”
Babies are generally born at week 36 to 41
Labor
Contractions of the uterus
May be short and “mild” or long and “agonizing”
Increase in frequency and pain as labor continues
May last 12 hours or more

10. This diagram tells it all…
The amniotic sac will break and the fluid leaks out
The cervix must dilate to 10 cm or 4 inches
The baby is still attached by the umbilical cord to the placenta
The uterus “pushes” the baby through the cervix and down the vagina
The umbilical cord is cut
The placenta is the afterbirth

11. Healthy Baby/Healthy Mother
A mother that mistreats her body is mistreating the baby
Dangerous substances in the mother’s blood can pass to the fetus
Illnesses, (viral infections)
Drugs
Nicotine, alcohol, caffeine